Problem: The scale on a map is 8cm : 7km. If the distance between two cities is 49km, how far apart in cm are the two cities on the map?
Answer: The scale means that every 8cm on the map corresponds to an actual distance of 7km. An actual distance of 49km is the same as 7 $\cdot$ 7km. The distance between the two cities on the map is 7 $\cdot$ 8cm, or 56cm.